The present disclosure relates to the technical field of display technology, and more particularly to an OLED pixel circuit and a method for retarding the aging of an OLED device.
An Active Matrix Organic Light Emitting Diode (AMOLED) is able to emit light because it is driven by current generated by a driving Thin Film Transistor (TFT) in a saturated state, and a conventional AMOLED pixel circuit is generally a 2T1C driving circuit. Referring to FIG. 1, the 2T1C circuit includes two TFTs and one capacitor, wherein T1 is a driving transistor of the pixel circuit, and T2 is a switching transistor; the switching transistor T2 is turned on by a scanning line Gate, the storage capacitor Cst is charged by a data voltage Vdata, and the switching transistor T2 is turned off during the light emission; and, the voltage stored in the capacitor keeps the driving transistor T1 turned on, and the turn-on current enables a Light Emitting Diode (OLED) to emit light. Since the OLED is in a DC biased state for a long period of time, ions inside the OLED are polarized to form a built-in electric field, so that the threshold voltage of the OLED increases constantly, the luminance of the OLED decreases constantly, and the service life of the OLED is thus shortened. In addition, since the DC biased voltage of the OLED is different in different gray levels, the degree of aging of the OLED in each sub-pixel is also different. Consequently, pictures displayed on the screen are not uniform, and the display effect is influenced.
In view of the problems in the 2T1C driving circuit, further improvements are made to the prior art to solve the problem that an OLED is in a DC biased state for a long period of time. However, many voltage control lines are generally required in an improved circuit, the control timing is relatively complicated, and the cost is greatly increased.
Thus, it is necessary to provide an OLED pixel circuit and a method for retarding the aging of an OLED device to overcome the problems existing in the conventional technology.